Fraunhofer: Laser technology for reducing solar cell manufacturing costs

Development opportunity

Fraunhofer researchers will be demonstrating laser technology that can reduce the manufacturing costs and optimise the efficiency of solar cells at Laser 2009 in Munich, Germany, from 15 to18 June.

Arnold Gillner, head of the microtechnology department at the Fraunhofer Institute for Laser Technology in Aachen, said, “Lasers work quickly, precisely, and without contact. In other words, they are an ideal tool for manufacturing fragile solar cells. In fact, lasers are already being used in production today, but there is still considerable room for process optimisation.”

In addition to gradually improving the manufacturing technology, the physicists and engineers in Aachen are working with solar cell developers – for example, at the Fraunhofer Institute for Solar Energy Systems ISE in Freiburg – on new engineering and design alternatives.

At Laser 2009 the researchers will be demonstrating how lasers can drill holes into silicon cells at speed. The ILT laser system drills more than 3,000 holes a second. “Our goal is to increase the performance to 10,000 holes a second,” said Gillner. This is the speed that must be reached in order to drill 10,000 to 20,000 holes into a wafer within the cycle time of the production machines.

The holes increase the increase the yield of the cells. “Previously, the electrical contacts were arranged on the top of the cells. The holes make it possible to move the contacts to the back, with the advantage that the electrodes, which currently act as a dark grid to absorb light, disappear. And so the energy yield increases,” Gillner said. With this technique it may in future be possible to use unpurified “dirty” silicon with poorer electrical properties, to manufacture solar cells.

Drilling holes is one many laser applications developed in the €6 million EU project Solasys – Next Generation Solar Cell and Module Laser Processing Systems.

The use of lasers technology in solar power manufacturing is just taking off, and it still has a long way to go. “Lasers simplify and optimise the manufacture of classic silicon and thin-film cells, and they allow the development of new design alternatives,” Gillner said.